55-year-old man killed, after he loses control of his motorcycle, on I-5 near Oceanside, and crashes into a guardrail.

A motorcyclist was killed in a crash at northbound Interstate 5 and state Route 78 in Oceanside Saturday morning, the California Highway Patrol reported.

The 55-year-old rider from Carlsbad was speeding on I-5 about 9 a.m. when he appeared to make a hard right as though he was attempting to transition onto the eastbound SR-78, said CHP Officer Jim Bettencourt.

The Harley-Davidson Sportster hit dirt in the transition, lost control and crashed into a guardrail. The motorcyclist, whose name was not released, died at the scene.

No other vehicles were involved. The crash remains under investigation.

One lane of freeway was closed during the investigation.